|
|
|
Poster Session Q
|
Geological – Structural and Matallogenic features of the Shuteen Ring Structure
B Delgertsogth
Institute of Geology and Mineral Resources, Sector of Regional Geology, P.O. BOX 37/58, Ulaanbaatar, Mongolua.
L. Daramsenqe
Institute of Geology and Mineral Resources, Group of Informatics, P.O. BOX 46/49, Ulaanbaatar, Mongolia.
Abstract
The Shuteen magmata ring structure 14 x 15 square km in size is situated in the Manglain fault systems of the Southern Mongolian Variscan fold belts. This structure is represented by a small subscrustal magmatic activity of late Carboniferous – Early Permain time. Volcanic rocks are composed mainly of andesite-dacite lava flows and their pyroclastic rocks. Within the above mentioned volcanic rocks numerous traces of the ancient volcanic activity are preserved. These include the caldron,. Vent, pipe and subvolcanical bodies. A buried igneous intrusion is located in southern eastern part of this structure and is dominated subalkalic biotite-plagioclase granite and granodiorite T. Sporadic occurrences of diorite and monzonite exist on the periphery.
Mostly terrigenous classic sediments of the Early Carboniferous age are developed in the N-NW part of the Shuteen ring structure and serve as its basement. The Shuteen ring structure is characterized by normal faults of circular and radial shapes. The relatively young fault system that trend NE played an important role in the development of this structure which is subdivided it into two tectonic blocks. The NW part of the structure downthrown while the other block is uplifted
System, which is distributed in the outer part of the Shuteen ring structure there are extensive hydrothermal alterations of various types.
The zones are associated with volcanic and plutonic rocks and contain auntie and porphyry copper mineralization. Application of remote sensing techniques gives us possibilities for obtaining new information about this structure.
Introduction
The Shuteen ring structure is about 525 km South of Ulaanbaatar city in the Umne-Gobi almag.
The area of this structure is covered by medium – and – large-scale geological survey completed after 1971. The important geological survey at a scale of 1:200000 was conducted by V.I. Goldenberg and specialize metallogenic investigations were done by D.Garamzhay and others.
In addition to the above-mentioned studies a large-scale survey and exploration was done during 1981-1983 on this structure. This study serves as the main source for this paper.
Geological position and its inner structure
In terms of regional and structrual geology of htis structure is situated in the Manlain fault system of the Gobi structural-and-for mention zone of the Southern Mongolian Variscan fold belts. The Shuteen ring structure is about 210 km2 in size and is represented small volcano-plutonic structures associated with the subcrustal magmata activity of Late Carboniferous-Early Permian time and is genetically connected with E-W Carboniferous – Early Permian time and is qunetically connected with E-W continental rift zones. Relatively young fault systems that strike NW-SE traverse the continental rift zones and these faults played a decisive role in the initiation of this structure. (Fig. 1) The Shuteen ring structure is composed mainly of andesite-dacite lava flows and pyroclastic sequences and of the buried igneous Shuteen instruction.
The latter consists of subalkalic and calcic-alkasline blotite-plagioclase granite and granodirite and sporadically of diorite and monzonite.
Terrigenous clastic sediments of Early Carboniferous age are developed in the N-NW part the Shuteen ring structure and serve as its basement. These were formed in the closing stages of development of the Southern Mongolian Varsican eugeosyncline basin. Layers of these sediments usually are dipping towards he central part of the Shuteen ring structure, which suggests considerable subsidence in its central where extensively developed hydrothermal-metasomatic alteration zones are closely associated with alunite and porpyry copper mineralization.
Features of the fault block structure
Within the area of this structure three major faults-blocks are distinguished. These are based on specific features of the geologic tectonic pattern and on erosion levels. ( See tale 1 and Fig. 2 ) The shuteen ring structure is subdivided into two major tectonic blocks by relatively young fault systems that strike NE-SW. The south-east sector of this fault-block is subdivided into two smaller blocks by faults that strike NW-SE.
the paper correlates four areas. (Chan Boqd. Char Tology, Dash Sum and Bayan Chushuu ) See table 2. )
The Char Tology, Dash, Sum, Bayan Chushuu and Dash Sum blocks are also correlated sot that we can use these three blocks for understanding this ring structure. The analysis of 8 elements within the four areas is also correlated (Cu, Mo,Ni,Co,Pb,Zn,Aq, As; see table 3). This geochemical analysis suggests independent copper mineralization. However, the Chan Boqd area has strong correlations of Mo and Zn, Ag and As suggesting some dominant mineralization. The Char Tolgoy area is dominated by a strong Mo and Zn correlation; but the Bayan Chushuu area shows strong Ag, As, Zn, and Mo
Table 2. Geologic Matallogenic characteristics of Shuteen ring structure.
Here all numbers are relative evaluations.
The correlation Analysis result between the block area.
|
|
|
|
|
|
|
